Dayton MA1240a Manuel D’Utilisation

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The MA1240a has two common or BUS inputs that 

receives audio signals from standard line-level audio 

sources and sends them to any or all channels. The BUS 

line outputs are direct feed-through to allow the BUS 

inputs to be fed to other amplifiers. Be sure to use high 

quality RCA cables that feature low impedance, shielding 

and high quality connectors.

This switch selects the turn-on stimuli that will put the ampli-

fier in ready mode. “Trigger” setting relies on 3-30V AC/DC 

voltage going into the trigger input to activate the amplifier. 

“Auto” setting senses a signal on the RCA line-level inputs 

and automatically puts the amp in ready mode. “On” setting 

puts the amp constantly in ready mode so that it can be 

controlled by the master power switch on the front panel. 

In “Auto” mode, the amplifier will take approximately 15 

minutes to return from ready to standby mode.

The trigger input is a handy feature when connecting the 

amplifier to an automated audio system. The 3.5mm mini-

plug jack will accept a 3-30V AC/DC output from another 

device, or from a separate power supply. When the trigger 

input is energized, the amp turns from standby to ON mode. 

When using the MA1240a with a receiver without a trigger 

output, the voltage can come from a 12V wall wart (3.5mm 

tip-positive connector) plugged into the receiver’s switched 

outlet and the trigger input. The MA1240a can also provide 

an output trigger voltage (12DC @500mA max.) to turn on 

and off other devices in the audio system. When the ampli-

fier turns off (standby mode), the voltage will drop to zero. 
Note: Remember there is a delay of approximately 15 

minutes before the amplifier goes to standby when using 

the “Auto” turn-on mode.

Each channel has its own independent level adjustment. 

This allows the output level of each speaker to be per-

fectly matched to its area. It can also be used to limit the 

maximum audio level in a certain area. 

By simply flipping a single switch, two channels can be 

combined to increase the total power output. This is helpful 

when extra power is needed in certain areas. 
Note: The minimum impedance for bridged channels is 8 

ohms. Also, please observe the proper speaker wiring when 

bridging channels. Input selection and volume settings for 

bridged channels will be controlled by the left channel. “BR” 

is bridged mode and “ST” is non-bridged or stereo mode. 
CAUTION:  Only change switch positions when the 

amplifier is turned off.

Each channel is capable of delivering the source from 

many inputs.  The three main inputs are BUS 1, BUS 2 

and LINE IN.  The selection for these inputs is done via 

the Input Selection switch associated with each channel.  

Select the desired source input.  Set the Input Selection 

switch to BUS 1 (will play source connected to the BUS 

1 input), BUS 2 (will play source connected to the BUS 

2 input) or LINE IN (will play source connected to that 

channel’s LINE IN). 
CAUTION:  Only change switch positions when the 

amplifier is turned off.

The MA1240a uses high quality Phoenix style connectors 

for the speaker connections. Use 14-18 gauge stranded 

two-conductor loudspeaker wire. Ensure that at least 

2 inches of each conductor are separated.  Strip away 

¼ inch of insulation from each conductor.  Connect the 

appropriate conductor to each screw terminal, observing 

correct polarity. Also, please observe proper speaker wir-

ing when bridging channels.

All twelve channels have their own dedicated input that 

allows the connection of audio sources in addition to 

the common BUS inputs. This is useful when using the 

MA1240a with an audio matrix switcher. 

The unit is set at the factory for 115V U.S. operation; simply 

connect the included IEC power cord to your wall outlet. 

For 230V operation, move the voltage selector switch to the 

230V position. When operating at 230V the internal fuse 

located in the IEC socket should also be changed. In most 

230V applications a separate power cord will be required 

and is not included.

The unit comes with an IEC jack that permits removal of 

the AC power cord. This allows the flexibility of changing 

the power cord for different countries. The IEC socket 

also houses the main fuse holder. Plug the power cord 

supplied with the amplifier into the amplifier and wall 

outlet or appropriate surge protector. 
CAUTION:  DO NOT plug the amplifier’s power cord into 

a switched outlet, such as what is provided on some Sur-

round Receivers.  If you wish to have the amplifier turn on 

when the Receiver is powered up, use one of the power 

modes, such as Trigger or Auto.